Summer is here, and grass is growing fast. Farmers and dealers are busy from morning to night. But high heat isn’t just hard on you – it’s a real test for your mower. Every July and August, our after‑sales team gets the same calls: “My mower suddenly lost power.” “The battery won’t charge.” “The engine stalled and white smoke came out.” Most of these problems are caused by working in extreme heat.
Whether your customers use petrol mowers or electric mowers, these summer tips are worth sharing. A few minutes of reading can save hundreds or even thousands of dollars in repair costs.
Part 1 – Petrol Mowers: Don’t Let the Engine Overheat
- The most important task: clean the cooling fins and housing
Many users change the oil regularly but never clean the engine’s cooling fins. Grass clippings, mud, and grease that build up on the fins act like a blanket – heat can’t escape, and cylinder head temperatures easily exceed 120°C (248°F). The result: oil thins out, lubrication fails, piston rings stick, and in severe cases the engine seizes.
How to do it: After each use, blow out the engine housing and cooling fins with compressed air or a pressure washer (keep pressure low, avoid the air filter and electrical parts). Pay special attention to the air intake around the starter cord – that area clogs first.
- Change to a summer‑grade oil
Engine oil thins faster in summer. If you’re still using the winter‑grade 5W‑30, the oil film may not be strong enough at high temperatures. Summer generally calls for SAE 30 (single grade) or 10W‑40 / 15W‑40. Check your manual, but the rule is: the high‑temperature viscosity should be at least 40.
Remember: Oil runs hotter in summer. Shorten the oil change interval from 50 hours to 25‑30 hours. The cost of one extra oil change is far less than an engine overhaul.
- Limit continuous running time – let the machine breathe
Many farmers run their mowers for four or five hours straight to get the job done. When the temperature is above 35°C (95°F), the cooling system starts struggling after 1.5 hours of continuous heavy load. Stop for 10‑15 minutes after every hour of work. When you stop, don’t kill the engine immediately – let it idle for 2 minutes so the cooling fan can keep pulling air, then shut it off. This prevents localised heat spikes that can warp the cylinder head.
- Check the air filter daily – more often in dusty conditions
Summer is dry and dusty. A clogged air filter makes the fuel mixture too rich, leading to incomplete combustion and even higher exhaust temperatures. In extreme cases, a red‑hot muffler can ignite dry grass – this is not a scare story. We hear about machines and even fields burning every year.
Recommendation: Check the air filter before starting each day. If the paper element is darkened or deformed, replace it immediately. Don’t blast a paper filter with compressed air – that blows holes in the micro‑pores and lets dust straight into the cylinder.
Part 2 – Electric Mowers (Lithium Battery): Heat is the Battery’s #1 Enemy
Lithium‑ion battery mowers are becoming more popular, but high heat damages lithium batteries more quietly and more permanently than cold. Once a battery swells or degrades from heat, replacement can cost nearly half the price of a new mower.
- Always let the battery cool down before charging
This is the most important rule: Never charge a hot battery right after use. Charging a battery at high temperatures causes internal short circuits, permanent capacity loss, and even thermal runaway (fire).
Correct practice: After mowing, remove the battery and let it sit in a cool, shaded place for at least 30‑60 minutes. Wait until it feels cool to the touch, then start charging. The ideal charging temperature is between 15‑30°C (59‑86°F). Never charge in direct sunlight, inside a hot car, or under a metal shed.
- Avoid “mowing in the sun”
When an electric mower is running, the battery naturally heats up. If the sun is beating directly on the battery compartment, ambient temperature can add another 10‑15°C. Cell temperatures can easily exceed 60°C (140°F). At that point, the Battery Management System (BMS) may shut off power to protect itself – the mower stops suddenly. Even if it doesn’t, discharge efficiency drops significantly: a battery that normally lasts one hour may run out in 30 minutes.
Advice: Mow in the early morning or late evening, avoiding the hottest midday hours. If you must mow at noon, try to shade the battery compartment (for example, with a reflective heat pad).
- Long‑term storage: don’t store fully charged or fully empty
Sometimes summer rains keep you from mowing for a week or two. During that time, keep the battery at about 40‑60% charge, stored in a cool, dry place (ideal temperature 10‑25°C / 50‑77°F). Storing at 100% accelerates aging. Storing fully discharged can cause over‑discharge, and the battery may “starve” to death – permanently unable to wake up.
- Keep cooling vents clear of grass clippings
Many electric mowers have cooling vents on the battery housing. Grass and mud can clog these vents during mowing. Every few days, check them and clean with a brush. A battery that works in a sealed, hot environment will have its life shortened by at least 30%.
Part 3 – Tips for both petrol and electric mowers
- Slightly lower tyre pressure: Summer ground temperatures can reach 50‑60°C (120‑140°F). Tyre pressure naturally rises. Inflate to about 90% of the standard recommended pressure to reduce blowout risk.
- Keep blades sharp: A dull blade requires more power to cut, which increases load on the engine or motor – and heat output. Sharpening blades in summer actually cools down the whole machine.
- Fire safety: Dry grass clippings against a hot muffler or motor housing can easily catch fire. Stop occasionally during work and clean out the built‑up debris under the deck. Keep a small fire extinguisher on your mower or vehicle.
A final word to dealers and farmers
Using a mower in summer comes down to four words: reduce load, increase cooling. Don’t treat your mower like an iron man – treat it well, and it will work for you for many summers. If you found this article useful, please share it with your customers or colleagues. Help more people save money and stay safe this summer.
